Police are looking for the killer of a Yale University graduate student, whose body was found behind a wall in the campus laboratory where she worked.

Twenty-four-year-old Annie Le's body was discovered at approximately 5 p.m. on Sunday on what was supposed to have been her wedding day. She had been missing since Tuesday.

Officials are calling the death a homicide.

"It's a frightening idea that there's a murderer walking around on campus," said 20-year-old chemistry student Muneeb Sultan. "I'm shocked that it happened in a Yale building that had key-card access. It's really sad."

The building where the body was found is accessible only to Yale employees with identification cards and is under constant surveillance by a network of 75 video cameras.

A friend of the slain graduate student said that while Le expressed concern over crime in New Haven, Conn. in an article she wrote last year, she never appeared to be worried about her personal safety at work.

"If she was concerned about (it) she would have said something to someone and they would have known," Jennifer Simpson told CBS' "The Early Show." "And Jon (her fiance) would have known, her family would have known, friends would have known."

Although students expressed sadness over Sunday's discovery, they said they feel just as safe as ever on Yale's campus.

"Obviously it's a city and there are safety concerns," said 18-year-old Peter Spaulding, a student from Maryland. "It can happen anywhere. You have to go on with life."

The university has scheduled a candlelight campus vigil for 8 p.m. on Monday.